You are here: The Difference Between Hot and Cold Riveting: Why Pull Rivet Nuts Fall Under Cold Riveting - CHANRUI
Within riveting processes, hot riveting and cold riveting are two entirely different technical routes. Many customers ask, when choosing automatic rivet nut guns or automatic riveting machines, whether their product should use hot or cold riveting and which category pull rivet nuts belong to. This article sets out the differences at three levels - principle, equipment and application scenarios - and why sheet metal, chassis/cabinets and new energy industries generally adopt cold riveting.
I. Key differences between hot and cold riveting
| Comparison Aspect | Hot Riveting | Cold Riveting |
|---|---|---|
| Forming principle | Heat the rivet until red-hot and upset-form while its plasticity is raised | At room temperature, cold-deform the fastener through pulling or pressing force |
| Heating needed | Heating equipment required (furnace, induction, electric riveting gun) | No heating needed; driven pneumatically/electrically/hydraulically |
| Typical fasteners | Solid rivets and semi-tubular rivets (large diameter, high-strength steel) | Blind rivets, pull rivet nuts and press-in fasteners |
| Impact on workpiece | Creates a heat-affected zone and may deform, discolor or damage the coating | No thermal deformation; assembly can follow painting |
| Operation mode | Usually double-side operation with a bucking bar, and high ambient temperature | Single-sided construction, handheld or automated |
| Typical applications | Bridges, vehicle chassis, heavy steel structures and large aviation parts | Chassis/cabinets, sheet metal, home appliances, auto parts and new energy |
II. Why pull rivet nuts belong to cold riveting
Pull rivet nuts are drawn axially by the gun-head screw at room temperature, which cold-extrudes the nut shank until it bulges on the backside of the plate - a typical cold-deformation (cold riveting) process; blind rivets that form by breaking the mandrel are cold riveting as well. Cold riveting generates no high temperature and will not cause plate warping, annealing or coating discoloration, so it is especially suitable for appearance parts that have already been painted, powder-coated or anodized, and for heat-conductive materials that deform easily when heated, such as aluminum and thin steel plate.
III. Why thin plates and automated lines mostly opt for cold riveting
First off,controllable deformation: thin plates warp very easily under heat, whereas cold riveting offers stable forming force and a flat plate surface; second,single-sided construction: the backside of chassis, square tubes and closed cavities cannot be reached, and hot riveting requires a bucking bar so it cannot be used there, whereas cold riveting finishes the job with a single gun; third,easy to automate: cold riveting offers a stable cycle, no heating wait and no open flame or fumes, which makes it easy to build auto-feed equipment or robot cells and suits batch lines; fourth,safer and cleaner: there is no high temperature, welding fume or fireproofing requirement, which delivers a better workshop environment and lower labor intensity.
IV. Common question: is cold riveting strong enough
For thin-plate joints, reliability is usually determined not by "hot or cold" but by the choice of fastener and the quality of forming. Structural blind rivets and hexagonal and knurled pull rivet nuts are widely used on automotive and new-energy structural parts, and their pull-out force and torque can be checked by specification and confirmed through coupon pull-out tests. Only genuine large-diameter, high-strength steel load-bearing joints (such as heavy frames and bridges) must use hot riveting. We advise telling the manufacturer the workpiece load requirements and choosing based on pull-out test data, rather than deciding on the impression that "hot is stronger". For pull rivet nut types, seeWhat Types of Pull Rivet Nuts: Type Comparison。
Hot and Cold Riveting FAQ
Process Choice FAQ
No, and there is no need. Automatic rivet nut guns are cold riveting equipment built for the cold deformation of pull rivet nuts; hot riveting calls for a hot riveting tong or a machine with a heating function.
Yes - this is one of the advantages of cold riveting, since assembly after painting does not damage the coating; simply control hole positions and the gun-seating angle per the process.
The deformation of pull rivet nuts is small and stays concentrated on the nut itself, with limited impact on the plate; conventional aluminum veneers and profiles show no abnormality over long-term use, and key load-bearing parts can be pull-out verified.
The two fasteners require different gun heads and forming principles, so automatic riveting machines and automatic rivet nut guns are usually configured separately; robot workstations can cover multiple processes by swapping guns.
Not sure which riveting process to use? Send samples for evaluation
Customers may book on-site visits to run cold riveting sampling and pull-out tests with real workpieces; consultation hotline +86 13268883882.
V. Can products already on hot riveting switch to cold riveting
Many traditional sheet-metal and vehicle parts were designed for hot riveting years ago; switching to cold riveting calls for three things: first, redesign the connection, replacing solid rivets with blind rivets or pull rivet nuts (positions that need later screw assembly should prioritize pull rivet nuts); second, verify strength through pull-out, shear and vibration tests per the original joint load requirements, confirming the substitution is feasible with data; third, assess the line - cold riveting needs no heating station or fume extraction, and the workshop layout is actually simpler. Products that are already thin plate, single-side reachable and assembled after painting usually gain in both deformation control and automation when switched to cold riveting, while large-diameter high-strength steel load-bearing joints should keep hot riveting. In mixed production, manage the two fastener types, hole types and tools separately to avoid misassembly.
Cold riveting saves the heating furnace, fume extraction and heat-resistant tooling, and handheld equipment carries a modest unit price; auto-feed and robot cells need higher investment, but measured against saved labor and energy, batch lines usually pay back quickly; we recommend trial-calculating per workpiece.
Recommended reading:Uses, Working Principle and Common Problems of Automatic Rivet Nut Guns · Blind Rivet Knowledge Summary · Automatic Rivet Nut Gun
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